It is known to manufacture polycrystalline silicon transistors in large area arrays on transparent crystalline substrates such as quartz. The quartz substrate is capable of withstanding thin film transistor processing steps at temperatures of about 800.degree.C. or higher but is also very expensive.
One approach to the reduction of substrate cost is to use a less expensive glass but this simultaneously requires a substantial reduction in processing temperatures and the use of new materials such as hydrogen doped amorphous silicon. Along with this reduction in processing temperatures comes a reduction in the yield of the fabrication process and the gains realized through a reduction in the substrate costs are at least partially offset.